Embossing process



United States Patent Oice i 3,170,008 Patented Feb. 16, 1965 3,170,008 EMBGSSING PROCESS i Alfred B. Levine, Chevy Chase, Mtl., assignor to Litton Systems, Inc., College Park, Md. Filed Mar. 14, 1961, Ser. No. 95,564 17 Claims. (Cl. 264-22) This invention generally relates to processes for produc'- ing designs and images on thermoplastic materials and is particularly concerned with thermoelectrical processes for reproducing art work, designs, and various other forms of intelligence by deforming the surface of a thermoplastic material in a pattern configuration corresponding tothe desired intelligence.

As used throughout this specification and claims, `the .terms deform and deforming are used in a broad context to mean a change-in physical shape or form terial. v

It is a principal object of the invention to provide a process for very accurately and precisely deforming the surface of` a thermoplastic material in a pattern correspondingto Vadesirel intelligence pattern.

`A further object is to provide such a process in which the'deforrnation pattern may be obtained in very'ne detail and with great definition.

of a ma- Another object is to provide such a process permitting Y permanent form or erased at will enablingnthe thermoi plastic to be used over and over again if desired.

Very generally according tothe inventionthere is provided a process for embossing Aordeforming a surface region of thermoplastic material according to a desired image or pattern by the combined use of'heat and electrically produced forces. In Vone `preferred embodiment, the pattern to be reproduced is obtained by first producing a two-dimensionalheat pattern of the configuration desired'overV the surface of the thermoplastic with the inftensity of heat being produced at each diiferentposition on the surface being` proportional to the depth of indentation or deformation to berproduced at that given position. This heat pattern serves to variably soften discrete positions Vof the thermoplastic material in the desired two-dimension pattern. In the next step, which may alsobe performed before or-coincidentally with the production `of the heat pattern, the entire surface region of the material for receiving the heat pattern is subjected to a strong electric field, producing a dielectric Aforce tending to defornjiV the thermoplastic. The intensity of the fieldv isvmade sufficiently great to deform or emboss the surface of the thermoplastic at these different positions that have been softened by the heat pattern but is not suflicient to deform the unheated Vregions of the plastic. In this manner, the surface regions of the plastic are variably deformed according to the predetermined image or pattern desired;

Other objects and additional 'advantages will be more readily understood by those skilled inthe art after a detailed consideration of the Afollowing specification taken with the accompanying drawings wherein:

FIGS. 1 to 3, inclusive, are schematic illustrations of a progressive series of steps for practicing the invention, in

' one form thereof;

FIG. 5 is a pictorial illustration of an alternative manner `of providing a latent heat pattern according to the iu- ,vention Y Referring now tothe drawings,l there is shown in FIGS. Vlto 4 one sequence ofrsteps that may be performed for embossing or producing a deformative pattern lsuchv as'` the letters ABC on the surface-of a thermoplastic member l 10 according to the invention. Y

As shown, in FIG. 1in the first step the upper surfaceA of plastic 10 is nonuniformly heated by a strong light ray,

infraredV beam or other suitable radiation indicated as 11 1n the configuration of the pattern which it is desiredY to emboss or deform on the thermoplastic material. The

nonuniform heat pattern may be obtained by such means y as masking aY source of the heating rays 11 through an opaque templet Vmember 12 with suitable cutout portions 13,- 14,'and 15 configured in the pattern of the letters ABC thereby permitting the heat rays to pass through the cutouts and'forrn a heat image 16 on the plastic `10. Alternatively, .the masking member 12 maybe a photographic transparencyhaving opaque and transparent areas therein in the desired pattern or anyother of thelmanyv knownmeans for projecting an enlarged vor diminished image of the pattern as known in the art.l

The heat radiation striking the thermoplastic in the pattern 16 desired is applied at a desired intensity and con-V tinued fora time durationthat Yis sufficient to Yvariably s often the heated portions of the surface in the configurat1on of the image 16,.thus.providing the upper surface of form ofsoftened areas in the plastic.

In the following steps as generallyfillustrated by FIGS.

theplasticwith a latent image-of the Ypattern Y16 in the e 2 and 3,. the plastic member 10 having the softened latent image 16 thercin isthensubjected to a uniform electric field being directed transversely through'the membernd exerting a uniforrndielectric lstressing of the member at each position along its surface. The electric Vfield prd- Aduces auniform dielectric stressing force in the plastic .member 10 that is normally insuiiicientito` distort the inemberf However, at those discrete. positions forming the `latent image16, the plastic has been sufficiently softened that the application of the transverse electric field produces a llow'of the plastic to create deformations therein inthe.

.form of ridges, valleys, Wrinkles' or the like 17, ,asf indicated1n FIG.,4, Thus, upon the.'applicationofy anfelectric field, the heat softened areas onthe plastic member are ldeformedtodevelop the latent heatiimage 16 intona ,configured pattern of embossing on the surfaceof the plastic vmember. Afterthe passage of a suicientperiod oftime to permit thethermoplastic to be. cooled, the heat ,softened areas thereon are again hardened to freeze Ythe deformed or embossed configuration in the plastic:as is desiredQ/,

In performing the steps of applying the uniform,electric field to stress the plasticas described, itis preferred that the upper surface of the plast-ic member rst be sprayed or wipedwith a negatively chargedl-ayer of electrons 18` frorna sultable source 19, as shown in FIGS. 2 andfand that thereafter the plastic member be subjected to a high intensity transverse electric field by such means asbeing placed between positive. and negative energized capacitor f plates 20 and ,21` that are connected toopposite'terminals FIG. 3 in assembled relationship, and v of a'high voltage direct ycurrent, sourceV 22. The high voltage positive plate 20 is placed underneathpthe plastic member 10 thereby attracting the electrons 18 on the surface of the plastic downwardly toward the plate 18` and in so doing exert thenecessary stress to deform the heat softened surface areas of the plastic member 10 as describedvaxboye. However, this intermediate step of negatively charging the surface of the plastic is not essential to deforming the plastic' and the application of afsuffiv ciently strong electricrfield., applied by the capacitor plates 3 20 and21 will deform the heat softened areas on the thermoplastic material.

As generally indicated above the cooling and consequent rehardening of the heat softened areas on the plastic vmember serves to freeze and permanently retain the Vdeformation pattern orimage in the plastic. However, if it is desired to erase this pattern and restore the plastic 'member to itsblank or undeformed condition, this may be easily'performed by uniformly heating the entire surface of the member 10 sufficiently lso that the plastic iiows to fill in the cavities, undulations, wrinkles 1'7 and the like formed in the embossed pattern. Alternatively, a large number of thermoplastic materials are known that possess a plastic memory and will return to their original shape and configuration upon the application of heat. By using these known materials, `the embossed or deformation pattern may be erased without the need for heating the member 10 until it reaches plastic fiow'or melted condition.

Although in the process steps as described above, the heat pattern is first applied to the plastic and thereafter an electric stressing force is applied to deform the heat softened area-s, it is believed evident that these steps may be reversed intime or applied simultaneously. By reversing the steps, the thermoplastic member may be first subjected toa uniform electric field that is insufficient to deform the hard plastic but does exert a sufficient dielectric force to deform the plastic as described after the application of the heat image thereto to variably soften the plastic. If the nonuniform heating and electric stressing steps are .applied simultaneously, the result is the same since the plastic will be deformed when it becomes softened. In thoseinstances where the two steps are applied simultaneously or where the electric field is applied first, the capacitor plates 2f) and 21 may be replaced by fine crossed wire grids or screens functioning as the capacitor elements to enable the heat radiation 11 to pass through Ithe open meshes of the grids to heat the plastic member.

By the process of the present invention, the deformation pattern or image being created on the thermoplastic member may be greatly enlarged or diminished in size 'from that of the templet or pattern means 12 by employing suitable optical lens and other known optical elements and projecting systems `for condensing or expanding the light or heat rays 11 to provide la larger or smaller reproduction of the heat image 16 `as Vmight be desired.

Alternatively, the heat-image 16 may be formed on the thermoplastic 10 in any desired pattern fby repetitively scanning lan extremely fine pencil beam of'radiation 24 overthe surface thereof in the desiredpath configuration as is illustrated in FIG. 5. As schematically shown in FIG. 5, a fine pencil beam 24 of intense heat radiation Vfrom the sun may be employed and focused by 'an eliptiical reector 25 or `other condensing and focusing system and this intense fine beam may be directed to scana desired heat pattern 16 on the thermoplastic 10 by positioning the reflector member 25 by means of a mechanical drive scanning mechanism 26 in the desired pattern. In this instance, the fine beam 24 may be repetitively traced `over the pattern-16 until the plastic 10 is sufficiently softened in'those areas to enable the deformation pattern to be formed on the plastic upon the later application of the electric field. Y Y

The deformation or embossed pattern may be obtained and frozen quite rapidly by applying a high intensity heat pattern for a short time interval and artificially cooling the material thereafter by suitable refrigeration or other known cooling means. Such a high intensity heat image may be yobtained from various radiant energy sources other than the suns rays, such as carbon are lamps or devices, photoash lamps, chemical orother exfplosions and the like.

of the material or layer of thermoplastic material ernployed.

With regard to the thermoplastic material to be ernployed, a wide variety lof dielectric thermoplastics are suitable such as various of the waxes, natural and synthetic resins, and various gelatinous materials, such as those formed of silicone oil.

Since these and many other variations and modications may be made by those skilled in the art, this invention is to ybe considered as being limited-only according to the following claims.

VWhat is clairnedis:

'1. A process for providing an image on-a thermoplastic member by deforming the surface of the mem-ber in a pattern corresponding to the image comprising the steps of producing a two-dimension heat pattern corresponding to the image, exposing a region of a thermoplastic record member to the heat pattern thereby to heat and raise the temperature of different discrete positions on the thermoplastic record in `a two-dimensional configuration according to the pattern of information to soften the record member at said discrete heated positions, and subjecting the region of the record member exposed to the heatpattern to an electric field of sufficient intensity producing a dielectric force to deform the thermoplasticfat the heated positions but of insuliicient intensitylto deform the un- 'heated positions thereon.

2. In the process of claim 1, the further step of erasing the deformation pattern onlthe record by reheatingthe record.

3. In the process of claim 2, the step of erasing the deformationl pattern being' produced by employing a thermoplastic material having a plastic memory whereby reheating of the record resoftens the material to permit the defformed positions-to return to theiry original condition.

4. In the process of claim l2, the step of erasing the "deformation 'patternbeing produced by reheating the thermoplastic material vsufficiently to enable plastic flow `of the material thereby to erase the deformation.

K 5. A process for'ernbossing a dielectric thermoplastic materialin a predetermined two-dimensional pattern comprising the `steps of 'nonuniforrnly heating different discrete positions over' a Vsurfaceregion ofthe materialin-a-pat tern configuration corresponding to the predetermined pattern, 'and subjecting the material to an electric field to deform the material at the positions receiving sufficient `heat but not the positions that have been insufiiciently heated.

6. In the process'of claim 5, the step of nonuniformly heating the different positions over the region being performed by lscanningthe region with a radiant beam in the pattern desired.

7. In the process of claim 5, the steps of nonuniformly heating the surface region of the material and subjecting A'heating the surface region-of the material being applied after subjecting the material to-the electric field.

`9. In the process of claim A8, the step of heating the materialbeing performed by scanning the surface thereof with a moving beam of radiant energy traveling in the predetermined configuration desired to heat those discrete Apositions on the surface where it impinges.

l0. In'the Vprocess of claim 9, the additional step of repetitively scanning the beam to trace the'surface pattern for ja variably predetermined number of cycles to obtain correspondingly variable depths of deformation of the pattern in the material.

for the electric field to deform the softened areas but not the remaining areas.

12. A process for embossing a dielectric thermoplastic material according to a desired intelligence pattern or design comprising .the combined steps of applying to the v material a nonuniform latent heat pattern in the desired configuration and subjecting the material to an electric force producing a dielectric stress whereby the combination of heat and electric stress produces an embossing of tbe material in the desired configuration, the additional step of varying the extent of deformation at different regions in the pattern, said Variable extent of deformation at different regions in the pattern being performed by applying Vto the material a heat pattern of nonuniform intensity whereby one heated region receives more heat than another heated region.

13. In theprocess of Vclaim l2, the step of applying the heat being performed by producing radiant energy beams in the spatial congurationdesired and at nonuniform intensities and applying said beams simultaneously to a region of the material.

14. In the process of claim l2, the step of applying the heat pattern being performed by scanning a ine beam of radiant energy over said material in the pattern desired.

15. In the process of claim 14, the step of scanning the beam being performed in such manner as to nonuniformly heat the material at different positions in the image.

16. A process for embossing a dielectric thermoplastic material according to a desired intelligence pattern or design comprising the combination of steps of applying thereto both a uniform electric field and a nonuniform heat pattern in the desired intelligence pattern whereby the electric field uniformly stresses the material and the heat pattern softens regions of the stressed material enabling deformation thereof; the step of applying the electric field being performed by depositing a uniform electric charge to the material over the region to be occupied by the pattern and subjecting the material to an opposite polarity electric potential at positions spaced from the charge thereby to impose an electric stress on the material in such region.

17. A process for providing a deformation image on a dielectric material that 4is absorptive of radiant Wave energy to become more plastic in the areas subjected to the Wave comprising thecombined steps of subjecting the material to the radiant wave in the pattern desired to provide a latent image of more plastic areas in the material, and subjecting a region of the material including the latent image areas to a dielectrically produced force to stress the material over said region sufliciently to deform the more plastic areas and therebyV develop the latent image but insuicient to deform the areas of said region that are not rendered more plastic by the Wave energy.

References Cited by the VExaminer UNITED STATES PATENTS 2,468,731 5/49 Borkland 41 -24 2,699,113 l/ Hoover 259-651 X v2,808,777 10/57 Roshkind Z50-65.1 X 2,825,814 3/58 `JJalkup 250-49.56 2,948,929 8/60 Stallard 41-24 X 3,055,606 9/ 62 Dreyfoos et al.

FOREIGN PATENTS 569,340 5/45 Great Britain.

OTHER REFERENCES February 1960, pages 76-79, TPRRecording, in Electronic Industries. g

ALEXANDER H. BRODMERKEL, Primary Examiner.

RALPH G. NILSON, MORRS LIEBEMAN, Examiners.ek 

1. A PROCESS FOR PROVIDING AN IMAGE ON A THERMOPLASTIC MEMBER BY DEFORMING THE SURFACE OF THE MEMBER IN A PATTERN CORRESPONDING TO THE IMAGE COMPRISING THE STEPS OF PRODUCING A TWO-DIMENSION HEAT PATTERN CORRESPONDING TO THE IMAGE, EXPOSING A REGION OF A THERMOPLASTIC RECORD MEMBER TO THE HEAT PATTERN THEREBY TO HEAT AND RAISE THE TEMPERATURE OF DIFFERENT DISCRETE POSITIONS ON THE THERMOPLASTIC RECORD IN A TWO-DIMENSION CONFIGURATION ACCORDINT TO THE PATTERN OF INFORMATION TO SOFTEN THE RECORD MEMBER AT SAID DISCRETE HEATED POSITIONS, AND SUBJECTING THE REGION OF THE RECORD MEMBER EXPOSED TO THE HEAT PATTERN TO AN ELECTRIC FIELD OF SUFFICIENT INTENSITY PRODUCING A DIELECTRIC FORCE TO DEFORM THE THERMOPLASTIC AT THE HEATED POSITIONS BUT OF INSUFFICIENT INTENSITY TO DEFORM THE UNHEATED POSITIONS THEREON. 